Exhaust Manifold I.D. Help

[Ron S.]

Readying for a new exhaust system on my '64 NOM convertible, 4 spd, no air. It has a 327 1968 vintage small block, believe from a Nova. Passenger side manifold is 3882461, drivers side manifold is 3872786. They are 2 ". I can't find reference anywhere to these numbers, so I just want to insure when ordering from any of the suppliers, that I get correct fitment. Trying to confirm if I order a '64 exhaust that it will fit properly. Thanks.
Ron

[Joe L.]

Re: Exhaust Manifold I.D. Help

Readying for a new exhaust system on my '64 NOM convertible, 4 spd, no air. It has a 327 1968 vintage small block, believe from a Nova. Passenger side manifold is 3882461, drivers side manifold is 3872786. They are 2 ". I can't find reference anywhere to these numbers, so I just want to insure when ordering from any of the suppliers, that I get correct fitment. Trying to confirm if I order a '64 exhaust that it will fit properly. Thanks.
Ron

Ron------


You're reading the numbers wrong which is very easy to do with casting numbers. Your right (passenger) side manifold is most likely a GM #3932461. This manifold was originally used on many 1969+ small blocks. It will function perfectly for your 1964 application and its configuration is quite similar to the original manifold except for one thing: It has fittings for AIR tubes. Some of these manifolds were made which had the AIR tube fitting BOSSES but without drilled and tapped fittings. I don't know which you have as casting number was the same.

Your left (driver) side manifold is most likely a GM #3872765. This manifold was used on 1966-71 Corvettes with AIR and left side alternator mounting. It will work fine for your application but it has the unused AIR fittings and the left side alternator bracket.

The correct manifolds for your application would depend upon whether you want the car to have 2" exhaust or 2-1/2" exhaust. Since you have a non-original motor there's no way to say which would be "correct" for your car as it stands now.